Sentry Purrscriptions, Dual Action Cat Flea & Tick Collar, Kills Fleas For Up To 6 Months & Ticks For Up To 3 Months, Fast Acting Kills Up To 98% Of Ticks Within 24 Hours, Long Lasting Protection, Injected Molded Collar With Notches To Fit The Collar Securely To Your Pet, Fits Necks Up To 14".